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Fig. 133 Epilithon membranaceum. A, carpogonia ( x 360). B, 

 conceptacle with ripe carpospores ( x 240). C, young antheridial 

 conceptacle ( X510). D, mature antheridial conceptacle ( X426). 

 Ej tetraspores ( x 228). F, G. thallus construaion ( x 360). (After 



KyUn.) 



Further divisions take place internally from the large basal cells so 

 that one finally obtains rows of erect filaments growing side by side. 

 The various reproductive organs are borne in conceptacles on 

 separate plants. The aggregation of the reproductive organs into 

 conceptacles must be regarded as equivalent to nemathecia which 

 subsequently become overgrown by surrounding tissue. In the 

 male plants there are a number of two-celled filaments in the centre 

 of each conceptacle. The basal cells of these threads cut off two 

 elongate antheridial mother cells, which in their turn produce two 

 antheridia. Antheridial mother cells are also produced from the 

 lower parts of the conceptacle walls. Since the entire antheridium 

 is Hberated as such it must be regarded as morphologically equi- 

 valent to a spermatium. In the female plant the central threads of a 

 conceptacle form three-celled carpogonial branches, the basal cell 

 of the branch being an auxihary cell. The outer threads of a con- 

 ceptacle produce sterile two-celled filaments. Only the central car- 

 pogonia mature and usually only one of these is fertilized and 

 produces carpospores. After fertihzation the carpogonium and the 

 cell below it fuse together and send out a filament to the lowest 

 cell (auxiliary cell). Later all the auxiliary and nutritive sterile cells 

 fuse to give one long fusion cell from which very short gonimoblast 

 filaments grow out. In the tetrasporic plant there are simple fila- 



239 



